The present invention relates to a canister inhaler for effectively delivering medications by inhalation through the mouth of patients having a flexible, elastic mouthpiece, a spacer for more effectively mixing the medication and air, and an easy to operate lever mechanism.
Inhalation into the lungs of a patient of a metered dose of medication is an increasingly common delivery system for a variety of drugs, including but not limited in any way to anti-asthma medications, insulin (See http://www.msnbc.com/news/525058.asp), various steroids and treatments specific to various pulmonary diseases. One concern with metered dose inhalers or aerosol pressurized cartridges has been that, while the metered dose inhaler canister dispenses a fixed, metered dose of medication, not all of the metered dose actually reaches the lungs of the patient. Even if a patient times inhalation with the dispersal of the medication from the metered dose inhaler (MDI), the amount of medication reaching the lungs is inconsistent, depending on how much of the medication is dissolved and entrained in the stream of air entering the patient""s lungs, and how much of the medication is deposited on surfaces of the inhalation apparatus, the mouth and oropharyngeal area of the patient. Furthermore, deposits in the mouth and oropharyngeal area of the patient can cause complications, such as candidiasis, as well as leave an unpleasant aftertaste. In addition, many patients using inhalation devices have practical problems with the use of typical inhalers, including difficulty with compressing the metered dose inhaler canister, problems timing inhalation with the dispersal of medication, and inability to inhale the complete dose of medication in a single breath, particularly young, elderly, or patients who suffer from asthma and dysphonia or thrush from inhaled corticosteroids. In practice, it is common to see patients activating their metered dose inhalers multiple times, although the metered dose should have been dispensed in a single activation. This is a typical response of patients to the difficulty and inconsistency of medication delivery, undermining the effectiveness of the MDI, which can lead to over-medication, under-medication, or waste and higher than necessary costs for treatment.
The typical solution to the problem of inconsistent medication delivery has been to provide a xe2x80x9cspacerxe2x80x9d or xe2x80x9cchamberxe2x80x9d within the inhalation device. A spacer or chamber is merely a reservoir of air. The metered dose of medication, usually an atomized mist or vapor, mixes with the reservoir of air before being inhaled by the patient, reducing the inconsistency of delivery due to timing difficulties. See U.S. Pat. Nos. 4,470,412; 4,790,305; 4,926,852; 5,012,803; 5,040,527; 5,042,467; 5,816,240; and 6,026,807. An additional improvement incorporated into many of the devices with spacers has been a simple valve mechanism to allow the patient to inhale the medication in more than one breath. For example, see U.S. Pat Nos. 4,470,412; 5,385,140. The efficacy of such devices for correcting errors in patient technique has been shown in general medical research. For example, see Demirkan, et al., xe2x80x9cSalmeterol Administration by Metered-Dose Inhaler Alone vs. Metered-Dose Inhaler Plus Valved Holding Chamber,xe2x80x9d Chest, 117 (2000) pp. 1314-1318, Finlay and Zuberbuhler, xe2x80x9cIn vitro comparison of beclomethasone and salbutamol metered-dose inhaler aerosols inhaled during pediatric tidal breathing from four valved holding chambers,xe2x80x9d Chest, 114 (1998) pp. 1676-1680, and Konig, xe2x80x9cSpacer devices used with metered-dose inhalers. Breakthrough or gimmick?xe2x80x9d Chest, 88 (1985) pp. 276-284.
One problem not generally addressed is the ease of compression of MDI canisters. One spacer, called the EZ Spacer(copyright), http://www.weez.com, improves the ease of compression by allowing the patient or another to use both thumbs on a pull handle and the forefingers on the MDI canister, but this is only a marginal improvement over the standard design, allowing merely one thumb and forefinger for compression of the MDI, and is no aid to patients who do not have full use of both of their thumbs and forefingers.
For infants or other patients who have difficulty using a mouthpiece, a mask is commonly attached or incorporated onto the MDI inhaler. See U.S. Pat. Nos. 4,809,692; 4,832,015; 5,012,804; 5,427,089; 5,645,049; 5,988,160. Also, some devices include an audible signaling device to warn patients when inhalation exceeds a desirable rate. For example, see U.S. Pat. Nos. 4,809,692 and 5,042,467.
One method of attaching a spacer to the MDI canister is to insert the MDI inhaler into a universal adapter such as shown in U.S. Pat. No. 5,848,588, but this is bulky and awkward to use, and does nothing to ease the difficulty of compressing the MDI canister for infirm or ailing patients. Other devices are designed to have a specific MDI canister inserted into the device. It would be beneficial to be able to insert MDI canisters for various medications into an inhaler with a universal receptor.
The present invention is directed to an inhaler that has universal receptors for at least one medication canister 10 or metered dose inhaler (MDI) canister, also referred to as a cartridge. By the term inhaler, the inventors mean that the device accepts a canister directly into the device, replacing the typical inhaler with an improved inhaler that comprises a receptor for an MDI canister, a spacer, an easy to operate lever arm, and a mouthpiece. One typical embodiment of the invention accepts a single canister, and has a lever arm 22 that is easy to depress, a chamber 210 that acts as a spacer (for example see FIGS. 9, 10 and 12), having an optional valve mechanism (for example see FIG. 11). In one embodiment, the optional valve mechanism is integrally molded with the chamber body and includes at least one inhalation vent 218 (for example see FIG. 12), a diaphragm valve 214, and an optional over-pressure whistle 212, which can be included to improve the efficiency of medication delivery by alerting the patient to improper inhalation technique. In another embodiment, the optional valve mechanism is fabricated separately from the chamber body, and the optional valve mechanism is then fixed to the chamber body. Examples of fixation include but are not limited to adhering, fastening, and inserting of the valve mechanism to the chamber body.
In one preferred embodiment of the mouthpiece, for example see FIG. 10, the mouthpiece 220 is comprised of a flexible, elastic material, and fits tightly around the chamber body 210 at the mouthpiece mating end 211. In one particular embodiment, an annular diaphragm valve 214 is positioned on a retaining member 215 in an optional valve mechanism within the chamber body. During inhalation, the diaphragm valve opens, allowing a mixture of air and medication to flow through at least one inhalation vent 218, then through the mouthpiece 220 and into the patient""s lungs. During exhalation, the diaphragm valve 220 closes, keeping the exhaled air from reentering the chamber body. Then, the exhaled air exerts an outward hydrostatic pressure against the sides of the mouthpiece 220. The hydrostatic pressure causes the exhaled air to escape by forcing the air between the mouthpiece 220 and the chamber body 210 at the mouthpiece mating end 211. In one particular embodiment, the mouthpiece mating end 211 has at least one exhaust port 216. In one particular embodiment the exhaust port 216 is a rectangular notch in the side of the mouthpiece mating end 216 of the chamber body 210, wherein the exhaust port 216 is covered by the flexible, elastic material of the mouthpiece 220. In this particular embodiment, the exhaled air preferentially exits through the exhaust port 216, because the flexible, elastic material of the mouthpiece 220 preferentially deflects at the location of the exhaust port 216. In another embodiment, as shown in FIG. 11, the mouthpiece 220 has an exhaust flap 223 or plurality of exhaust flaps defined by slits 224 in the flexible elastic material of the mouthpiece 220, such that the exhaust port 216 or plurality of exhaust ports are covered by the flexible, elastic material of the exhaust flap 223 or plurality of exhaust flaps 220.
In a typical embodiment, the flexible, elastic material fits tightly around the chamber body, sealing the exhaust ports, until the hydrostatic pressure during exhalation becomes great enough to cause exhaled air to be forced between the chamber body and the flexible, elastic material of the mouthpiece. It is preferred that the flexible, elastic material thickness be selected to require at least some minimal exhalation pressure before air escapes between the mouthpiece and the chamber body.
One preferred embodiment of the mouthpiece is comprised of silicone rubber. In addition, other flexible, elastic materials can be used including, but not limited to, butyl rubber, neoprene rubber and latex. The parameters important in the selection of the flexible, elastic material to be used include both the composition and the thickness of the flexible, elastic material. The material should be durable and have sufficient elastic tensile strength to be useful, including resisting normal wear and tear and also holding firmly onto the chamber body when stretched around the outer surface of the chamber body. Furthermore, if the flexible, elastic material is used for the portion of the mouthpiece that the patient inserts into his or her mouth, then the material should be rigid enough to allow the patient to form a tight seal around the mouthpiece during inhalation and exhalation. Alternatively, a rigid insert could be placed within the portion of the mouthpiece that the patient inserts within his or her mouth, and the rigid insert in combination with the flexible, elastic material could be rigid enough to allow the patient to form a tight seal around the mouthpiece during inhalation and exhalation. In yet another embodiment, the rigid insert could extend within the flexible, elastic material completely, except for the flexible, elastic material covering the exhalation ports. In this particular embodiment, the rigid insert could be, for example, could make no contact with the chamber body, could contact the chamber body without fixation, or could be fixed to the chamber body.
In a preferred embodiment, the flexible, elastic material is flexible enough to allow the exhaled air to escape between the mouthpiece and the chamber body at a useful exhalation pressure. The exhalation pressure is greater than zero pounds per square inch (psi) or zero inches of water above the ambient pressure, but the exhalation pressure can be very low, and should be designed to be practical for use by patients with breathing difficulties. By a very low exhaust pressure, the inventors mean that the exhaust pressure is greater than zero and just sufficient to cause exhaust air to exit the mouthpiece between the flexible, elastic material and the chamber body at an exhaust port. The exhaust port can be located very near to the edge of the flexible, elastic material. One typical embodiment had an exhaust pressure less than 2 inches of water above the ambient pressure, but this is not an absolute limit. Indeed, selection of materials, thickness, the presence of exhaust tabs and exhaust tab attachment and exhaust port size and location would allow any practical exhaust pressure to be chosen. Practical minimum and maximum inhalation and exhalation pressures are known in the art or can be determined readily from the preferences of specific drug manufacturers.
When very low exhalation pressure is desirable, it may be beneficial to have a raised lip on the end of the chamber body engaging the mouthpiece. Then, the flexible, elastic material can be made thinner and can be stretched over the lip, helping to retain the mouthpiece on the chamber body. In one particular embodiment of the invention, the exhaust port in the chamber body does not interrupt the lip which extends completely around the chamber body. In this particular embodiment, the mouthpiece is designed to stretch over the lip, and the edge of the mouthpiece is shaped to fit the chamber body. In a preferred embodiment, a retaining ring is used to couple the mouthpiece onto the chamber body. For example, the retaining ring can be positioned over the flexible, elastic material of the mouthpiece where it engages the chamber body, such that the retaining ring couples the mouthpiece and chamber body, more securely fixing the mouthpiece to the chamber body than would be possible by merely relying on the elasticity of the mouthpiece to hold itself on the chamber body. The position of the retaining ring must not interfere with the functioning of the exhaust ports. In one embodiment, this is accomplished by extending the flexible, elastic material of the mouthpiece beyond the retaining ring, such that the flexible, elastic material is free to deform, functioning as an exhaust flap over the exhaust vent. In one embodiment, the edge of the mouthpiece extends at least 0.01 inches beyond the end of the exhaust vent in the chamber body, whereby the exhaust vent is completely covered by the flexible, elastic material of the mouthpiece. In one preferred embodiment, the edge of the mouthpiece extends at least 0.125 inches beyond the end of the exhaust vent. In an alternative embodiment, an exhaust tab is defined by the absence of flexible, elastic material surrounding the exhaust tab, which exhaust tab covers an exhaust port and both the exhaust tab and exhaust port are located between the retaining ring near the end to the mouthpiece and the end of the chamber body on the mouthpiece mating end of the chamber body, such that the retaining ring does not interfere with the functioning of the exhaust port. In this alternative embodiment, the exhaust flap is integrally fixed to the rest of the mouthpiece, but is defined by the removal of flexible, elastic material on one or more sides of the exhaust tab. For example, a square tab can be defined by removal of material on three sides of a square of material, while leaving one side of the square attached to the rest of the flexible, elastic material. It should be clear to one of ordinary skill in the art, that the tab can be defined by any absence of material, even if on only one side, because the flexible, elastic material can expand outward under the exhalation pressure of the patient, allowing air to escape from between the exhaust port and the tab. Therefore, the tab need not be a flap, but can be a mere hole in the flexible, elastic material. In a preferred embodiment of this alternative embodiment, the tab is defined by an absence of flexible, elastic material, except for a connection on one side of the tab that connects the exhaust tab to the rest of the flexible, elastic mouthpiece.
Alternatively, the chamber body could have a depression in the surface. For example, the depression could be a groove around the chamber body at the mouthpiece mating end of the chamber body. Then, a raised rib around the inside of the flexible, elastic material of the mouthpiece could engage the depression in the surface of the chamber body, interlocking the mouthpiece and the chamber body. The groove in the chamber body and raised rib on the mouthpiece could act to secure the mouthpiece onto the chamber body, allowing use of a thinner material than would otherwise be practical for securing the mouthpiece to the chamber body. Alternatively, a retaining ring could be used to mate with the depression in the chamber body, coupling the mouthpiece to the chamber body.
In another alternative embodiment, a structured exhaust valve can be used that comprises an exhaust port and additional structure. A xe2x80x9cstructured exhaust valvexe2x80x9d is used to describe an exhaust valve that is more than merely an exhaust port in the surface of the chamber body, directing the exhaled air through an exhaust vent, which directs the exhaled air, for example, to a limited region near the end of the exhaust flap defined by slits in the flexible, elastic material.
In addition, a flexible, elastic material that is both inert to the contents of the MDI and nontoxic to the patient is preferred. By inert, the inventors mean that the flexible, elastic material avoids any substantial chemical reactivity with the contents of the MDI. Substantial chemical reactivity is defined functionally, such that a substantial chemical reaction is one that causes a severe degradation of the mouthpiece. Such chemical reactions and compatibilities of flexible, elastic materials with medications used in inhalers are known in the art.
A severe degradation of the mouthpiece renders the mouthpiece unusable including, but not limited thereto, to causing an unhealthy or toxic contamination of the mouthpiece or medication passing through the mouthpiece, or causing a failure of the mouthpiece to function, for example impeding flow of air through an exhalation vent, allowing air to leak into the exhaust port during inhalation, or sticking an exhaust flap to the surface of the chamber body. Severe degradation can be caused by embrittling, tackifying, or softening of the flexible, elastic material. By tackifying, the inventors mean that the flexible, elastic material undergoes a chemical reaction that causes the surface of the flexible, elastic material to become xe2x80x9ctacky,xe2x80x9d which means that the surface becomes sticky to the surface of the chamber body. Embrittling causes the material to become rigid impeding flow of air or to crack allowing inhaled air to enter through an exhaust port. Softening causes the material to lose its rigidity and tensile strength, losing its shape or its ability to grip the chamber body with sufficient force to remain in place on the chamber body.
Tests for chemical reactivity are notoriously well known to one of ordinary skill in the art. Tests can be performed to determine if a specific material is chemically inert to a specific medication or to an array of medications. In one method of testing, samples of the material can be exposed to one or more medications and changes in the physical or chemical properties of the material can be measured to determine compatibility. For example, chemical reactivity can be revealed by endothermic or exothermic heat transfer following contact of a material with a specific medication. Also, changes in color of a material, changes in the composition of a material, and changes in the weight, volume or other physical properties of a material can be observed as indicators of chemical incompatibility. One of ordinary skill in the art should be familiar with the techniques required to assess chemical compatibility between a material and a medication.
In addition, one possible embodiment could use additives in the flexible, elastic material or coatings on the surface of the flexible, elastic material to arrest or reduce to acceptable levels any undesirable chemical reaction between a material and a medication.
Another typical embodiment of the invention accepts two canisters (dual canisters), and has a lever arm 22 that is easy to depress, a chamber 24 that acts as a spacer, and a mouthpiece 25, having an optional valve mechanism 62 and over-pressure whistle 63, that improves the efficiency of medication delivery, and a slidable selector switch 21 that permits the user to select the mode of operation. The modes of operation include selecting either of the two canisters individually. An additional non-operational setting locks the actuator lever 23 to prevent inadvertent dispensing of medication during periods of non-use.
One object of the invention benefits patients who are infirm or young, by reducing the difficulty in using an inhalation device. The actuator lever 23 allows the entire hand to be used in depressing the MDI canister, and also provides a mechanical advantage, reducing the pressure necessary to dispense the medication. The sliding selector switch 21, for example of a dual canister embodiment, is easy to manipulate, and can be put into position to operate either of the dual canisters individually with one hand. The optional locking position can also be selected by a patient with only one hand. An optional indicator shows which of the two canisters is selected by the sliding selector switch.
In a preferred embodiment of the multi-canister inhaler, the dual canister design allows two different kinds of medication to be dispensed by a single inhaler. Increasingly, patients require multiple MDI medications, and the use of a single inhaler for two different medications, which reside conveniently within the inhaler, reduces problems with storage, retrieval, and insertion of MDI canisters into the inhaler for those that are infirm, young or in distress. Alternatively, the second canister may be inserted as a reserve supply for those patients that require assistance with insertion of canisters into an inhalation device, allowing the patient to switch to the reserve supply by merely pushing the sliding selector switch.
In one embodiment, the standard, universal cowling is designed to accept MDI canisters of nearly all commonly prescribed medications, and the cowling helps to guide the canister into the inlet port of the housing when the patient inserts a MDI canister into the inhaler. In addition, the cowling provides support to the canister when the patient depresses the actuator lever, dispensing medication into the housing of the inhaler. Specialized cowlings may be designed for unusual MDI canisters or new MDI canisters that would not fit the universal cowling. By universal, the inventors mean that the cowling is designed to accept nearly all commonly prescribed MDI canisters.
Upon dispensing the medication, the atomized mist from the inhaler is directed through the housing and into the chamber. During inhalation by the patient in one typical embodiment of the invention, a vent in the housing brings fresh air into the housing sweeping the remaining atomized mist from the housing into the chamber, where it mixes with the air, and is drawn into the patients lungs through the patients mouth. In one preferred embodiment of the invention a valve assembly in the mouthpiece of the chamber allows the mixture of medication and air to be drawn through the mouthpiece during inhalation, see FIG. 8, for example, but during exhalation, the inhalation valve closes, and an exhalation valve opens, allowing the exhaled air to escape from an exhalation vent in the mouthpiece. This allows the patient to inhale the medication in multiple breaths.
It should be obvious to one of ordinary skill in the art that an inhaler with access ports for more than two canisters could be configured in the same way as the dual canister design shown in the figures, and presented in the detailed description of the invention. Indeed, the invention is not limited to a dual canister design, but would include a multiple canister design, which includes a sliding selector switch able to engage each of the multiple MDI canisters inserted into an expanded cowling.